1. Field of the Invention
This invention relates to a container or the like for cleaning preparations comprising a fused closure which consists of a stopper disposed in a closure hole of the container, more especially in the cover thereof. The stopper comprises a material which melts at a predetermined temperature, e.g., paraffin, and which releases the closure hole for the exit of a product packaged in the container. A ring is raised towards the axis of the closure hole integrally formed with the peripheral surface of the closure hole and with a sealing film holding the unmelted stopper in place.
2. Description of Related Art
Liquid-tight fused closures are used in product containers which are to be opened at a certain temperature in a closed space in the course of a given process. For example, containers having a fused closure are used for packaging machine care preparations intended for use in dishwashing machines. In such a case, the unopened container is introduced into the machine compartment. The machine is then switched on after closure of the machine compartment. In order to prevent the machine-care product from issuing prematurely from the container, the constituent material of the fused closure is selected in such a way that the stopper only melts at the temperature most favorable to the use of the product, i.e., the product only enters the machine compartment at that time. In addition, the stopper should not be able to slide out of its position in the closure hole of the container without melting. Accordingly, a collar raised towards the axis of the closure hole has been integrally formed around the peripheral surface of the closure hole in order to hold the stopper in place.
During the stoppage of closed product containers of the type herein, undesirable leaking of the product can occur between the peripheral surface of the closure hole and the stopper as a result of variations in temperature. This effect occurs in particular where the product is one which has a tendency to leak combined with a strong wetting action. One reason for the leakage of product is that minute gaps are formed through variations in temperature between the wall or peripheral surface of the closure hole and the fused stopper disposed, more especially cast, herein, through which the product is able to leak, optionally via the collar.
This problem may be eliminated by adapting the thermal expansion coefficients of the materials adjoining one another in the region of the stopper. However, since the choice of material for the container and the fused closure is determined by a number of other requirements, for example, temperature stability and melting point, mechanical stability, chemical stability and the like, it is only possible to strike a more or less acceptable compromise when adapting the temperature coefficients.
If a product container effectively sealed by the fused closure is obtained in accordance with the foregoing, an excess pressure can be expected to build up inside the container in the event of an increase in temperature of gas-evolving products below the melting temperature of the stopper. In some cases, the excess pressure even acts on the stopper. The constituent material of the stopper is generally relatively soft at elevated temperature because it is intended to melt in the event of a further increase in temperature. In the event of significant variations in temperatures, for example, as during day and night, it can happen that the stopper acts a pump through alternating excess pressure and reduced pressure and outwardly transports product adhering to the inner surface of the stopper.
The object of this invention, in general, is to provide a seal which prevents the premature emergence of the product stored in the container and which is effective even despite a difference in temperature expansion behavior between the container or cover wall on the one hand and the stopper disposed in the closure hole of the container on the other hand. In particular, the invention seeks to prevent the position of the stopper relative to the closure hole from being changed by temperature-induced changes in the pressure prevailing inside the container.